Toxicology Flashcards
What are antidotes to beta blocker and CCB toxicity?
Intralipid
Insulin and dextrose
Glucagon
Calcium (for CCBs)
Vasopressors
What is the typical illness script for a Copperhead bite?
Usually, it happens on a hand or foot. The initial symptoms are localized swelling and redness. The worst symptoms happen at 18-36 hours after the bite.
When should you treat a Copperhead bite with CroFab?
If someone has skin/MSK findings that progress past a joint line or they are having concerning progression of symptoms.
When should you use a tourniquet or suction on a snakebite?
Never. Tourniquets can cause concentrated tissue necrosis. Suction (with or without cutting) can cause localized inflammation that can deepen the path of venom into the wound.
True or false: baby snake bites are worse than adult bites.
False
When should you admit a person with a snake bite?
If you’ve given antivenom, recommend an observational admission.
How long after giving antivenom should you wait to reassess before redosing?
About 30 minutes It takes 30-60 minutes after finishing the bolus to reach peak effect.
When evaluating a snake bite, look for _____________.
oozing at fang marks – this is a reliable sign of envenomation
What are the two types of venomous snakes in the US?
Crotaline (copperheads, rattlesnakes) and Elapidae (coral snakes)
Crotaline toxin causes what lab abnormalities?
Thrombocytopenia and elevated INR
What immediate management should you do with snake bites?
- Immobilize the limb
- Remove jewelry on the affected limb
- Mark the leading edge of erythema
What physical exam things should you look for in a snake bite?
- Fang marks with oozing (sign of envenomation)
- Progression of erythema/edema
- Compartment syndrome
The mean age of people dying from opiates is ______.
37
Starting MAT in someone presenting from an overdose in the ED has been shown to decrease 1 year mortality by ___________.
59%
What are the side effects of methadone?
- Prolonged QT
- Tooth decay
True or false: methadone is a partial agonist.
False Buprenorphine is a partial opioid agonist. Methadone is a full agonist.
True or false: buprenorphine is a potent respiratory depressant.
False
Because it is a partial agonist, buprenorphine has a high ceiling of respiratory effects. It will typically only cause apnea if combined with something else.
You should only start buprenorphine when your patient is ___________.
in withdrawal
Because buprenorphine is a partial agonist, it can precipitate withdrawal if someone is still high.
Describe the screening process for lead toxicity in children.
Kids are screened with a capillary stick. If this is elevated (greater than 5 ug/dl) then you confirm with a venous lead. If the venous is 5-45 ug/dl you council on prevention strategies and rescreen later. If the venous is greater than 45 ug/dl you begin chelation therapy.
In general, when you see that someone is having unpleasant side effects from a drug but their levels are normal, try ______________.
decreasing the dose
Learning point: the drug level isn’t everything. You can have side effects at any dose.
____________ are the first-line treatment for PCP-associated agitation.
Benzodiazepines
Haldol as backup.
Saw palmetto is commonly used to treat as a supplement for what?
BPH
What are side effects of saw palmetto?
GI upset and increased bleeding risk
What are side effects of ginseng?
Increased bleeding risk
___________ (a supplement for post-menopausal hot flashes) can cause hepatotoxicity.
Black cohosh
Kava can cause ______________.
liver injury
What supplement (that is also a food) can cause hypokalemia?
Licorice
What is the big difference between CCB toxicity and beta blocker toxicity?
CCBs cause hyperglycemia whereas BBs cause hypoglycemia.
Review the protocol for treating radiation exposure.
The first and most important thing is to decontaminate the person exposed. Their clothing is likely radiating, so you need to remove all clothing and wash them down. Only when their Geiger readings are ≤ 2x the background radiation can they safely be around other people.
What factors portend a poor prognosis in acute radiation syndrome?
Early GI symptoms
48 hour ALC < 1.5
Those with a rising salicylate level on recheck may need what therapy?
Hemodialysis
If you need to make a bicarbonate solution, do not use what IV solution?
Normal saline
Bicarbonate solution has high amounts of sodium, and if you add it to a NS solution then you will make them hypernatremic.
The toxic level of acetaminophen is _______ mg/kg.
150
So for a 70 kg adult it is 10 g.
Review the management of puss moth caterpillar injuries.
Puss moth caterpillars are insects covered in a toupee-like fuzz. They are found in the eastern US. They can release venom from their stings that then causes local tissue injury.
Manage by using tape to remove any unseen spines stuck in the skin. Wash the area with soap and water. Numb with topical lidocaine. Support with NSAIDs and antihistamines.
What is a beta particle?
It is a high energy electron or positron that can cause damage.
Why is it a good idea to distance yourself from radiation sources?
The amount of exposure is inversely proportional to the square of the distance, so doubling your distance decreases the exposure by a factor of four.
Why is polonium used in poisonings (like the KGB did to Litvinenko in 2006)?
Polonium is the last radioactive element in the decay chain of uranium before lead. It only emits alpha particles, so if you put it in a vial it will be undetectable and not harmful to anyone. It is only harmful if ingested.
The three mantras of limiting radiation exposure for healthcare workers is what?
Time, distance, shielding
Limit your time around the person, increase the distance, and wear shielding
What is the priority of decontamination by body site?
1st: wounds
2nd: orifices
3rd: intact skin
Acute radiation syndrome can begin at what radiation exposure level?
0.2 Gy for hematopoietic effect, 1 Gy for clinical symptoms
The first lab abnormality to show up in acute radiation syndrome is what?
ALC drop (within 48 hours if clinically significant)
Vomiting within _______ after a radiation exposure is suggestive of lethal dose of radiation.
1 hour
If you are concerned about radiation sickness, a good resource is _______________.
Radiation Emergency Medical Management (REMN); they have an app
Explain dry decontamination.
Water can activate some substances, so if there is physically something visible on the patient you should attempt to brush it off dry before using water.
Tide pod ingestion should be treated with what?
Water
Laundry detergent is alkaline. Water helps dilute it.
Review the management options for beta-blocker overdose.
- For hypotension: IV fluids and vasopressors
- For refractory shock: high-dose insulin, calcium salts
- For hypoglycemia: glucagon
- For coma: lipid emulsion
What drug can mimic opioid overdose?
Clonidine
It causes apnea, hypotension, lethargy, and miosis.
The treatment for organophosphate poisoning is _____________.
atropine (titrated to secretions) and pralidoxime (2-PAM)
What is 2-PAM?
2-pyridine aldoxime methylchloride (aka, pralidoxime)
Sarin gas has what toxidrome?
Cholinergic
What order do you need to given atropine and pralidoxime?
Atropine then pralidoxime
Pralidoxime reactivates acetylcholinesterase, but it temporarily inhibits it first, thereby worsening cholinergic symptoms. Atropine should be given first to decrease this effect.
Review the cholinergic toxidrome.
Bradycardia
Bronchospasm
Sialorrhea
Lacrimation
Urinary incontinence
Delirium
GI distress
Eyes (miosis, just remember it’s the opposite of atropine)
Sweating
What is the dose of atropine for organophosphate toxicity?
2 mg
Double dose every 3 minutes until they no longer have wheezing or bronchorrhea.
Which toxidrome antidote has to be given quickly or else it won’t work?
Pralidoxime
If there is a significant delay after exposure to organophosphates then the toxin-acetylcholinesterase compound “ages” and gets less amenable to reversal.
What toxin can cause optic neuritis?
Methanol
What physical exam finding is seen in lead toxicity?
Burton’s line – a line of gray-blue discoloration of the gingiva next to the teeth
Which antiepileptic can cause AGMA in toxic levels?
Topiramate
What metabolite accounts for the AGMA seen in methanol ingestion?
Formic acid
Cholinergic toxicity is seen in what two scenarios?
- Organophosphates (farm workers)
- Dementia patients (who take rivastigmine or donepezil)
CPRHHH is what toxidrome?
Opioid
- Coma
- Pinpoint pupils
- Respiratory depression
- Hypotension
- Hypothermia
- Hyporeflexia
What antidote would you give someone who had a wide-complex tachycardia after huffing an inhalant?
Esmolol
The hydrocarbons in inhalants are thought to induce dysrhythmias by over-sensitization to catecholamines.
What is scombroidosis?
Histamine fish toxicity
This is a reaction in which fish is left out and the meat produces more histamine. It then can induce urticaria when eaten.
Which parts of the GI tract are more likely injured by acidic agents vs alkaline agents?
Stomach
In acidic ingestions, the acid causes coagulative necrosis of the esophagus which often creates an eschar that prevents deep injury of the esophagus. The acid then goes to the stomach where it dwells for a long time and can penetrate the normal barriers that protect against acidity.
Alkali agents, on the other hand, cause liquefactive necrosis in the esophagus which can quickly cause deep injury of the esophagus.
In symptomatic caustic ingestions, when should endoscopy take place?
12-24 hours
Beforehand is too soon and risks reinjuring the tissue. After then is too late and may miss important findings.
Why should you not use saline to remove organic foreign bodies (such as seeds or insects)?
Saline is hypertonic compared to most living things, so it can cause organic matter to swell and make removal more difficult.
Why are button batteries harmful?
They generate a small amount of electrical current when against mucous membranes, and that current produces hydroxide ions that cause liquefactive necrosis. Both poles of the battery can be harmful, but the negative pole is worse.
What is the natural history of iron toxicity if untreated?
- (30 minutes to 6 hours) Iron first causes GI symptoms due to irritation of the GI mucosa.
- (6-24 hours) GI symptoms usually resolve.
- (12-72 hours) Patients develop AGMA, AKI, and coagulopathy.
- (24-96 hours) Next an ALI develops.
- (Weeks) GI scarring can occur.
True or false: iron toxicity causes neurologic symptoms such as cognitive impairment and ataxia.
False
These are associated with lead.
What are the indications for iron chelation therapy?
- Severe symptoms (e.g., intractable N/V/D, obtunded, or severe AGMA)
- Iron level greater than 500 mcg/dL (regardless of symptoms)
Absence of what symptom in the first six hours after lead ingestion is predictive of good prognosis?
Vomiting
What is the antidote for anticholinergic toxicity?
Physostigmine
Dystonic reactions happen more commonly in which patients?
Younger patients (due to the decline of dopamine receptors)
A salicylate level greater than __________ indicates hemodialysis.
100 mg/dL acute or 60 mg/dL chronic
Review the symptoms of salicylate toxicity.
Tinnitus
AGMA
Respiratory alkalosis
Coma
Non-cardiogenic pulmonary edema
What toxin is said to smell like burning rope?
Cyanide
Overdose of oxymetazoline can mimic what toxidrome?
Clonidine
Oxymetazoline is primarily an alpha-1 agonist, but it also has partial alpha-2 agonism.
What is the molecule in computer cleaner that people huff?
It is difluoroethane, a type of halogenated hydrocarbon
Which alcohols cause a gap and non-gap acidosis?
Non-gap: isopropyl alcohol
Gap: ethanol, ethylene glycol, and methanol
A long-term complication of iron overdose is ______________.
pyloric stenosis
Iron causes peroxide formation of the lipid membranes in the GI tract. This can cause scarring of the stomach.
Review the stages of iron toxicity.
I:
- 0-6 hours
- GI irritation (abdominal pain)
II:
- 6-24 hours
- asymptomatic
III:
- 12-24 hours
- Metabolic acidosis w/ compensatory tachypnea; AMS
IV:
- 24-96 hours
- Liver failure with hypoglycemia
V:
- >96 hours
- GI strictures
Succimer is given for which toxicities?
Lead, arsenic, and mercury
What is the typical alcohol clearance rate?
20-30 mg/dl per hour
True or false: activated charcoal is indicated in the management of alkali ingestion.
False
Alkali ingestion can cause esophageal perforations. A patient should be NPO because anything ending up in the mediastinum (including charcoal) can make it worse.
Early endoscopy is warranted.
What are the mechanisms of salicylate toxicity?
- The main mechanism is the uncoupling of oxidative phosphorylation within mitochondria. This leads to ineffective aerobic metabolism which produces lactic acidosis.
- It also directly stimulates the medullary respiratory center that then causes respiratory alkalosis.
What is the mechanism of iron toxicity?
In excessive amounts it leads to lipid peroxidation of cell membranes.
Sudden coma after consuming apricot kernels?
Cyanide poisoning
What homeotherapy can cause salicylate toxicity?
Oil of wintergreen
Review the pathophysiology of ethylene glycol toxicity.
Ethylene glycol gets metabolized to oxalic acid, which causes an AGMA. Oxalic acid then precipitates in urine to form calcium oxalate crystals.
How do you calculate osmolarity?
(Na x 2 ) + (BUN / 2.8) + (glucose /18)
Why is salicylate toxicity so harmful to fetuses?
- The fetal pH is slightly higher. When un-ionized salicylate enters fetal circulation it donates a proton and gets trapped, thus accumulating in the fetus.
- Fetuses cannot hyperventilate, so they are less able to counteract the metabolic acidosis of salicylate toxicity.
- Salicylate moves bilirubin off of albumin and can induce kernicterus.
- Like all NSAIDs, salicylates inhiibit prostaglandin synthesis and can cause premature closure of the ductus arteriosus.
What gas is produced in silos?
Nitrogen dioxide
It is a reddish-brown gas that can cause methemoglobinemia.
What is the dose of naloxone?
0.4 - 2.0 mg IV Q2Min
What metabolite is responsible for the toxic effects of methanol?
Formic acid
True or false: isopropyl alcohol does not cause ketosis.
False
Isopropyl alcohol causes ketosis with no acidosis.
What is the toxic dose of aspirin
200 mg/kg
What is the toxic dose of aspirin
200 mg/kg
What lead level warrants chelation therapy regardless of symptoms?
Greater than 70 ug/dL
Think of Led Zeppelin in the 70s
What are the salicylate levels for HD in acute and chronic ingestions?
Acute: 100 mg/dL
Chronic: 50 mg/dL
What is the mechanism for isoniazid-induced seizures?
Isoniazid inhibits the production of pyridoxine which is a cofactor in the production of GABA.
What is the mechanism of black widow venom?
It induces the release of acetylcholine and norepinephrine at NMJ, causing muscle cramping.
What toxidrome does the gas that smells like cut grass cause?
Phosgene causes lung injury with pulmonary edema.
Where does methanol exposure come from?
Windshield wiper fluid
(Think of ants crawling on a windshield.)
In which cases would you consider multiple-dose activated charcoal?
In cases of medicines with high enterohepatic recirculation (like phenytoin)
Why does aspirin overdose lead to fever?
The uncoupling of oxidative phosphorylation leads to fever.
What are the levels of salicylates that necessitate HD?
Acute: > 100 mg/dl
Chronic: > 50 mg/dl
What are the indications of iron chelating therapy for toxic ingestion?
Iron levels > 500 mcg/dl
Acidosis not attributable to another cause
Shock
AMS
Refractory GI symptoms
Which opioid can cause mydriasis in toxic doses?
Meperidine
Which toxidrome presents with heat disturbances, ciguatera or scromboid?
Ciguatera
“Ciguatera can’t feel the CIGarette.”
How is the management of scromboid different than ciguatera?
Scromboid is a histamine reaction and requires antihiistamines. Ciguatera is supportive only.
A person wakes suddenly after presenting comatose and with bradycardia. Toxin?
GHB
What is the mechanism of brodifacoum?
It is a long-acting anticoagulant that works by inhibiting the vitamin K cycle. It causes delayed and prolonged coagulopathy.
What is the dosing of DigiFAB for cardiac arrest?
5 vials for children and 10 for adults
True or false: activated charcoal is not indicated in caustic ingestions.
True
When do you give parenteral NAC for acetaminophen overdose?
Vomiting (i.e., can’t tolerate PO NAC) and pregnancy
What toxin do castor beans contain?
Ricin
However, excessive mastication is needed to make it dangerous. Ingestions of whole beans are not usually dangerous.
Ketosis without acidosis is seen in what ingestion?
Isopropyl alcohol
Isopropyl alcohol gets metabolized to acetone which creates ketones but is not acidic.
Which drug causes coma with intermittent periods of agitation?
Gamma hydroxybutyrate (GHB)
Which agent smells like hay?
Phosgene
(“pHAYsgene”)
How does glucagon treat beta blocker overdose?
It stimulates the production of cAMP which counteracts beta blockers.
What is the best initial test to determine the severity of iron toxicity?
Serum iron level drawn 4-6 hours after ingestion
True or false: isolated benzodiazepine overdose causes respiratory depression.
False
Similar to alcohol overdose, people with benzodiazepine overdose will usually have normal vitals (if isolated).
What are the three ways drugs can cause liver injury? Provide examples.
Direct, indirect, and idiosyncratic.
Direct injury refers to drugs that have a dose-dependent toxic effect on the liver. Acetaminophen and methotrexate fall in this category.
Indirect refers to physiologic effects of drugs that can cause secondary liver injury. Things like immune checkpoint inhibitors can cause autoimmune hepatitis.
Idiosyncratic refers to drugs that most often cause no liver injury but in rare cases for unknown reasons cause liver injury. Augmentin and other antibiotics can cause this.
True or false: all DILI is hepatocellular pattern.
False
High direct bilirubin can result.
What substances do not require decontamination?
Gases that are fully aerosolized (like Cl)
Why do you need to irrigate wet cement exposures?
They have alkali chemicals and can cause burns.
What toxidrome presents with burning of the skin, CVA, HTN, miosis, and seizure?
Ergotism
What gas causes silo lung?
Nitrogen dioxide
True or false: an asymptomatic child who ingested household bleach does not require an early endoscopy.
True
Household bleach is a dilute sodium hypochlorite solution that does not often cause esophageal burns. If a child is well appearing, controlling their secretions, and tolerating po then they do not need an endoscopy.
What medication other than fomepizole can treat ethylene glycol toxicity?
Thiamine and pyridoxine
Hydrogen peroxide ingestion might necessitate what treatment?
Hyperbaric oxygen
Hydrogen peroxide creates air emboli that can cause stroke.
What is the difference between absorb and adsorb?
Adsorb means molecules stick to the surface, whereas absorb means molecules penetrate into a substance.
What substances are not treatable with charcoal?
Heavy metals (e.g., iron, arsenic)
Ions (e.g., lithium, potassium)
Alcohols (e.g., ethylene glycol, methanol)
Gasoline
Caustic substances (acid or alkali)
What management is needed for oral ingestion of elemental mercury (think old thermometer or chemistry set)?
Nothing
Elemental mercury is highly lipophilic. When it is ingested there is nearly no GI absorption. Elemental mercury can be inhaled, though, so if there is significant time breathing mercury toxicity can develop.
The most common mercury poisonings occur from mercury salts (say, PhMe oor dimethylmercury) in food.
What is the mechanism of isoniazid-induced seizures?
Pyridoxine is necessary for the synthesis of GABA.
What is the best indicator of mortality in digoxin overdose?
Hyperkalemia
What is the classic presentation of Amanita phalloides ingestion?
Asymptomatic period followed by delayed GI symptoms
What is an ingestion for which delayed charcoal administration (after 12 hours) is recommended?
Amanita phalliodes (thought to interrupt enterohepatic recirculation)
Which toxic gases can have a delayed effect and require observation?
Irritant gases like phosgene can have delayed onset up to 24 hours
What toxicity is treatable with L-carnitine?
Valproate
L-carnitine specifically treats hyperammonemia.
Review the ranges of lead serum values:
- Normal
- Abnormal but no chelation required as long as no severe symptoms
- Optional chelation
- Mandatory chelation
- Normal: less than 5 mcg/dL
- Abnormal but no chelation as long as no severe symptoms: 5 - 19 mcg/dL
- Optional chelation: 20-44 mcg/dL
- Mandatory chelation: greater than 45
What toxidrome presents with hyperalgesia, paresthesias, and generalized weakness?
Ciguatoxin
(“CIGuatoxin makes your skin feel burned by CIGarettes.”)
What treatment can you give to people with G6PD who have methemoglobinemia?
pRBCs
How many hours post-ingestion is an EGD indicated after caustic ingestion?
12-24 hours
It takes time for the injury to manifest on EGD.
Botulism antitoxin is not recommended in which group?
Babies
Which anticoaguluant is dialzyable?
Dabigatran
What are two treatments for arsenic?
Succimer (oral)
Dimercaprol (IM)
What can doing a VBG and ABG tell you about toxin ingestion?
Cyanide toxicity causes the cells to be unable to use oxygen, so classically the PaO2 is unchanged from VBG to ABG.
Other than local wound findings and coagulopathy, Copperhead bites also cause what symptom?
Metallic taste – think COPPERhead
Cold allodynia (sensation of hot and cold switched) is pathognomonic for which toxidrome?
Ciguatera
What should you give to someone who ingested isopropyl alcohol?
PPI or famotidine
Isopropyl alcohol can cause hemorrhagic gastritis.
What three treatments can you give to those with severe methanol toxicity?
Folinic acid
Fomepizole
HD
True or false: obtain a repeat digoxin level one hour after administration of DigiFAB.
False
DigiFAB falsely elevates the level of digoxin, meaning only the clinical response can be used to determine if additional doses are needed.
What fish can cause scrombroid?
Tuna
Mackerel
Bonito
What fish can cause scrombroid?
Tuna
Mackerel
Bonito
When do the platelets, neutrophils, and hgb nadir after exposure to ionizing radiation?
30 days
Which syndrome is mediated by histidine, scombroid or ciguatera?
Scombroid
“Scistamine”
